User accounts are managed through the Windows Control Panel. If you don't have access to Control Panel, read this article.
Steps

Step 1. Open "My Computer" and in the search bar enter "Control Panel" (without the quotes)
If that didn't work, go to step 2.

Step 2. Click "Start" - "Control Panel"
If that didn't work (or Control Panel isn't in the menu), go to step 3.

Step 3. Click "Start" - "Run" or press Windows + R
Enter Control Panel. If that didn't work, go to step 4.

Step 4. Open a command prompt
Click Start - Run and type cmd. In the Command Prompt window, enter Control Panel. If that doesn't work, go to step 5, but don't close the Command Prompt window.

Step 5. At the command line, enter net for information about this command
- To change your password, enter net user (username) * (don't forget the asterisk).
- To add a user enter net user (username) / ADD
- To delete a user enter net user (username) / DELETE
- Enter net accounts /? For information on the net accounts command. You can use this command to force logout and set expiration dates for user accounts.
- If you need more options, enter /? At the end of each command described. Or search the Internet for information on using a particular command.
Method 1 of 1: How to add a user using the command line

1 net user [username [password | *] [options]] [/ domain]

2 username {password | *} / add [options] [/ domain]

3 username [/ delete] [/ domain]